Several phonological oppositions are typically accompanied by F0 differences. F0 is higher following voiceless consonants than voiced; it is also higher for high than low vowels. Analysis of cricothyroid activity aimed to determine whether these F0 differences are automatic effects contingent on the basic articulatory manoeuvres required for the oppositions of voicing and vowel height, or whether the differences reflect active enhancement strategies. Results for both oppositions suggest a hybrid model: The articulatory contingency is at the heart of the F0 differences, but these differences may be reinforced by active laryngeal adjustments. Additional analysis focused on German tense vs. lax vowels. Higher cricothyroid activity in lax vowels could explain why these vowels do not follow typical intrinsic F0 patterns. Tentative support was found.